JSON序列化有问题，全局设置，UnrecognizedPropertyException: Unrecognized field Spring Boot ObjectMapper 配置不生效问题

红太狼 2024-05-02 20:20 57阅读 0赞

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### 问题 ###

后台接收 `Json` 参数时有以下要求：

*  指定时间格式
 *  忽略不识别的字段
 *  忽略不识别的枚举

一般是配置 ObjectMapper 即可生效

#### 配置 ObjectMapper ####

@Bean
    @Primary
    public ObjectMapper objectMapper() {
        return new ObjectMapper()
                .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                .enable(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)
                .setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
    }

如上配置没有生效

#### 配置 Jackson2ObjectMapperBuilderCustomizer ####

@Bean
    @Primary
    public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {
        return builder -> builder
                .featuresToDisable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                .featuresToEnable(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)
                .simpleDateFormat("yyyy-MM-dd HH:mm:ss");
    }

也不生效

### 解决方案 ###

> 解决方案引用自 [Jackson2ObjectMapperBuilderCustomizer不生效解决][Jackson2ObjectMapperBuilderCustomizer]

不生效的原因一般是 `MappingJackson2HttpMessageConverter` 对象在程序启动时创建了多个，我们只要将多余的去掉，并重新添加 `MappingJackson2HttpMessageConverter` 的 bean 就可以了

#### 问题根源 ####

基础包中配置了 `MappingJackson2HttpMessageConverter`，导致应用服务工程中配置的 `ObjectMapper` 无效

@Configuration
    public class WebMvcConfig implements WebMvcConfigurer {
    
        @Autowired
        private RequestApiInterceptor requestApiInterceptor;
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
            registry.addInterceptor(requestApiInterceptor).addPathPatterns("/**");
        }
    
        @Bean
        public RequestApiInterceptor restfulApiInterceptor() {
            return new RequestApiInterceptor();
        }
    
        /**
         * 解决controller返回string类型数据错误
         */
        @Override
        public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
            converters.add(0, new MappingJackson2HttpMessageConverter());
        }
    }

#### 关键代码 ####

在应用服务工程中按如下配置功能生效

@Configuration
    public class ConvertConfiguration implements WebMvcConfigurer {
    
        public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
            ObjectMapper objectMapper = new ObjectMapper()
                .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                .enable(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)
                .setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
            return new MappingJackson2HttpMessageConverter(objectMapper);
        }
    
        @Override
        public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
            converters.removeIf(MappingJackson2HttpMessageConverter.class::isInstance);
            converters.add(0, mappingJackson2HttpMessageConverter());
        }
    
    }

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com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field

场景：项目升级后突然访问接口提示com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field

原因：前端传的json对象在转化实体类bean时，有多余的属性值，解析不了

几种解决方法：

第一种：在指定类上添加属性如下属性

@JsonIgnoreProperties(ignoreUnknown = true)

第二种：全局配置

package org.activiti.rest.conf;
     
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
     
    import com.fasterxml.jackson.databind.DeserializationFeature;
    import com.fasterxml.jackson.databind.ObjectMapper;
     
    /**
     * @author Joram Barrez
     */
    @Configuration
    public class JacksonConfiguration {
     
        @Bean()
        public ObjectMapper objectMapper() {
            
            ObjectMapper mapper = new ObjectMapper();
          
            mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false); 
            return mapper;
        }
    }

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[Jackson2ObjectMapperBuilderCustomizer]: https://link.segmentfault.com/?enc=lWUR5OyzKQruwpUduU%2BtYQ%3D%3D.%2B7%2BrZnfLhNJeYxZt0spTiJiGFHrZuaGQv1sSUKcv8oe9e1URmO1a9ulf%2Bu9D4V%2FUlqBVV5Clwbf%2FgUaVwycyPQ%3D%3D
[com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException_ Unrecognized field_love_-CSDN]: https://blog.csdn.net/qq_38423256/article/details/123880292